"Little" Steven Van Zandt is on a mission: to save rock'n'roll from extinction. "If the Rolling Stones came out today, there's not one radio station in America that could play them," says Van Zandt, currently dividing his time between filming the last season of The Sopranos (he plays Silvio Dante), being the guitarist for Bruce Springsteen's re-formed E Street Band, and recording his weekly Underground Garage radio show. "The Rolling Stones wouldn't fit anybody's format! How did we end up in a world where there's a format for everything apart from rock'n'roll?"

Van Zandt claims that rock'n'roll is his religion, and as he talks with messianic fervour about the importance of saving America by ensuring it doesn't lose the music of its youth, you have no reason to doubt his faith. With his paisley bandanna and psychedelic shirt, Little Steven certainly doesn't look as if he's been paid a visit by the Queer Eye for the Straight Guy team.

His headquarters, on a stretch of Manhattan that looks out over the Hudson river, is filled with B-movie posters, records in their thousands, and a Sopranos pinball machine. And Underground Garage, his two-hour show that plays modern garage bands alongside both obscure and famous rock'n'roll from the 1950s, 60s and 70s, is a nationwide hit that's currently syndicated to an audience of around a million. But when Van Zandt and his producer Dan Neer approached stations and syndicators five years ago, every single one rejected them.

"There was one thing missing in all the radio station statistics," says Van Zandt. "It's called human nature. I was told that the audiences are leaving and you had to give people familiarity. But there's a reason why the audiences are going away from mainstream radio. It sucks! There's a generation out there that needed to hear cool radio of the kind I grew up on, and a ridiculous egomaniac like me was needed to give it to them."

The idea for Underground Garage began in 2000, after a seven-year fallow period in Van Zandt's life was ended by the discovery of a thriving garage-rock scene coming out of New York City. Having organised the Sun City anti-apartheid concerts, played guitar for Bruce Springsteen and released solo albums throughout the 1980s, Van Zandt entered the 1990s to find Mandela released, Springsteen going solo, and music, in his opinion, taking a turn for the worse. "I moved away from music at that point and did nothing. I literally walked the dog for seven years," he says. "Then an old friend of mine came up to me one day and said: 'You know that band I was in as a teenager in the 1960s? Richard and the Young Lions? Somebody's putting our single on a compilation. Now we're re-forming and doing a gig next week.' It turned out that there was this whole scene I knew nothing about."

The compilation was the Nuggets box set; a collection of mid-60s singles by mostly teenage bands that drew their inspiration from British invasion groups such as the Rolling Stones, the Kinks and the Beatles. Some, like Open Up Your Door by Richard and the Young Lions, were modest hits, but most were obscurities to be unearthed as forgotten gems decades later. It was the kind of music that Van Zandt had grown up on and first learned to play on the guitar.

"We didn't call it garage at the time," he says. "Back then I just knew I was hearing great songs on the radio, whether that was a soul track like Knock on Wood by Eddie Floyd or a garage single like Talk Talk by the Music Machine." The idea of garage as a genre was born in 1972 when Patti Smith's guitarist Lenny Kaye compiled the original Nuggets album. It featured great songs by mostly one-hit wonders like the Standells and the Shadows of Knight. "Garage bands were linked by a snotty attitude and a sense of teenage frustration. And the fact that they knew the Rolling Stones were the coolest band in the world."

Van Zandt's enthusiasm is infectious, even if you didn't already know that 96 Tears by ? and the Mysterians is the best song ever written. He sees the Ramones, the much-loved, much-missed punk heroes of New York, as the cornerstone of all the music he champions. "I like everyone who influenced the Ramones and everyone the Ramones influenced," he says. So, having heralded the return of rock'n'roll radio, championed a generation of new bands and held down day jobs in The Sopranos and Springsteen's band, what's next? "I need to get Underground Garage on in Britain because England seems to be full of arty romantic stuff right now, like Coldplay and Radiohead. You know, it's great, God bless them all. But it ain't rock'n'roll."

Need to know First record bought: Duke of Earl by Gene Chandler Favourite film: Performance Record to grab in an emergency: The London Sessions by the Rolling Stones Inspiration: 1960s radio DJ Alan Freed Recent discovery: Hawaii Mudbombers